JPH05178685A - Floating zone melting device - Google Patents

Abstract

PURPOSE:To greatly improve the temp. distribution within a horizontal plane and to enable the growth of a good-quality large-sized single crystal by changing the shape of a reflection mirror of ellipsoidal surface of revolution in a radiation concentration heater of the optical floating zone melting device into a specific shape. CONSTITUTION:An IR lamp 1 is provided on one focus of the reflection mirror 2 of ellipsoidal surface of revolution having the reflection surface on its inside surface and a melting part 3 on the other focus. The radiations reflected from the reflection surface are concentrated to this melting part to melt the part. The reflection mirror 2 of the such heater is made to the shape in which the sectional shape has the shape of ellipsoidal surface of revolution and the entire part has the annular shape. After a raw material bar 4, a seed crystal 5 and a quartz mirror 6 are set, the lamp 1 is lighted and while the bar 4 and the seed crystal 4 are rotated, the voltage impressed to the lamp is gradually increased to melt the front end of the raw material bar 4. The bar 4 and the seed crystal 5 are thereafter brought near to each other until both are joined via the melting part 3. The bar 4 and the seed crystal 6 are slowly moved downward at a prescribed speed while the voltage impressed to the lamp is adjusted, by which the bar-shaped single crystal is grown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention concentrates infrared rays emitted from an infrared lamp such as a halogen lamp as its radiant rays by using a spheroidal reflector to obtain a high temperature to grow a single crystal or a phase. The present invention relates to a so-called concentrated radiation heating device useful for equilibrium research and the like.

[0002]

2. Description of the Related Art Conventionally, a radiation concentrated heating apparatus has been well known in the fields of single crystal growth, phase equilibrium research, and the like.
The sample can be melted without using a crucible, (2) the atmosphere gas can be arbitrarily selected, (3) the single crystal growth of various compositions can be easily performed by using the floating zone method,
(4) Performing phase equilibrium studies by the floating zone annealing method,
(5) It has advantages such as high temperature can be easily obtained with relatively little electric power, and it has been widely used in a research apparatus for growing single crystals and phase equilibrium.

Recently, a new oxide superconductor has been discovered and research is actively conducted. In this case as well, growth of a single crystal is desired in order to clarify the nature of the substance, and floating is required. We have succeeded in growing large single crystals of some substances using a zone melting device. However, it is difficult to grow a series of oxide superconductor single crystals containing yttrium and bismuth, and although fine crystals have been synthesized, with regard to large single crystal growth that can withstand full-scale physical property measurement, There is no success case yet.

A conventional infrared concentrated heating type floating zone melting apparatus uses one or two spheroidal reflecting mirrors (in some cases, there are four), and by using this, the light of a halogen lamp or a xenon lamp is used. Is focused at a focus position to obtain a high temperature to grow a single crystal.When one spheroidal reflector is used, a lamp is provided at one of the two focal points of the spheroidal reflector. , Is designed to provide the sample to be melted at the remaining focus positions. When two spheroidal reflectors are used, they are basically arranged in the same manner as in one case, but in this case, the major axis directions of the two spheroidal mirrors are arranged on the same line,
By sharing the focal point where the sample should be provided,
It is designed to collect the light of two lamps at the same position to melt the sample.

The conventional floating zone melting apparatus designed as described above has the advantages that a relatively high light collection efficiency can be achieved and a relatively high temperature can be easily obtained. It has been used for research on intermetallic compounds. However, in the above floating zone melting apparatus, theoretically the temperature distribution in the horizontal plane of the sample should be constant due to the use of the spheroidal reflector, but in reality, the filament of the lamp Due to the shape effect and the shape effect of the lamp itself, the temperature distribution in the horizontal plane, which is the most important for single crystal growth, is not constant. For this reason, the reality is that rotation is added to improve the temperature distribution. And in the case of a system that requires a very strictly controlled temperature distribution, such as the case of the above oxide superconductor, due to the nonuniformity of this temperature distribution, even if rotation is performed, a high quality is obtained. However, it is extremely difficult to grow the large single crystal.

The present invention is intended to solve the above-mentioned problems of the conventional optical floating zone melting apparatus, and provides a new optical floating zone melting apparatus capable of greatly improving the temperature distribution in the horizontal plane. It is intended to be provided.

[0007]

In order to solve the above-mentioned problems, the present invention is to change the shape of a spheroidal reflecting mirror so as to improve the temperature distribution in a horizontal plane. An infrared lamp is installed at one of the focal points of the spheroidal reflecting mirror that is used as a reflecting surface, and the radiant rays reflected from the reflecting surface are concentrated and heated on the other focal point. The present invention provides an optical floating zone melting apparatus, characterized in that the mirror has a spheroidal shape in its cross section and has a special shape which is entirely ring-shaped.

The present invention is also an improvement in the detailed structure thereof. Hereinafter, the device of the present invention will be described in more detail with reference to the accompanying drawings.

[0009]

1 and 2 are a front view and a side view showing the concept of an infrared concentrated heating type floating zone melting apparatus according to the present invention, and FIG. 3 is an enlarged view of a main part. In FIGS. 1 and 2, 1 is a halogen lamp, 2 is an elliptical reflecting mirror, and 3 is the point where the light of the lamp is concentrated, which corresponds to the melting portion of the sample. Reference numeral 4 is a raw material rod, 5 is a grown crystal, 6 is a transparent quartz tube forming a sample chamber, 7 is a raw material rod supporting portion, 8 is a grown crystal supporting portion, 9 is a raw material rod supporting shaft drive portion, and 10 is a grown crystal. The support shaft drive unit 11 is a device stand. In this apparatus, the raw material rod 4 is first attached to the raw material rod supporting portion.
The seed crystal 5 is set on the growing crystal support part, and the quartz tube 6
After turning on the lamp 1, turn on the lamp 1,
With 10, the voltage applied to the lamp is gradually increased while rotating the raw material rod and the seed rod, and the tip portion of the raw material rod 4 is melted. When the tip of the raw material rod 4 is melted, the driving device 9, 1
By moving 0, the raw material rod and the seed rod are brought close to each other, and both are joined via the fusion zone. The fusion zone is held by its surface tension so as not to fall. Using the upper and lower driving units 9 and 10 while adjusting the voltage applied to the lamp, when the raw material rod and the seed rod are slowly moved downward at the same speed and at a predetermined speed, the raw material rod is melted and the crystals on the seed rod are melted. The growth is continued and the rod-shaped single crystal is grown.

At this time, if the temperature distribution in the horizontal plane is poor as in the conventional apparatus, no matter how much the growth crystal drive shaft 10 is rotated, as it passes through the nonuniform temperature portion,
Growth and dissolution of crystals are alternately repeated, and good quality single crystals are not grown. However, according to the present invention, as shown in FIG. 3 in an enlarged manner, the infrared lamp 1 is provided at one focus of the spheroidal reflecting mirror 2 having an inner surface as a reflecting surface, and the melting portion is provided at the other focus. In the radiant ray concentrated heating device of the type in which 3 is provided and the radiation reflected from the reflecting surface is concentrated and heated, the spheroidal reflecting mirror 2 has a spheroidal shape as its cross section, and Has a ring-shaped special shape, the temperature distribution in the horizontal plane is almost ideal for growing a single crystal, and thus a good-quality single crystal can be grown.

Further, another one of the features of the new floating zone melting apparatus according to the present invention is that the condensing efficiency of the halogen lamp is remarkably improved, and therefore the temperature gradient of the object to be heated becomes steep. This is an advantage that the falling of the melt, which is the most important for growing a single crystal with a diameter, is unlikely to occur. Since the conventional floating zone melting method is a method of holding the formed melt on the sample itself, the amount of the melt that can be stably held is limited by the correlation between the surface tension of the melt and the specific gravity of the melt. However, there is a drawback in that it is difficult to grow a large-diameter single crystal. However, by using the device of the present invention, it becomes possible to grow a large single crystal having a much larger diameter than ever before. Utilization as a production device will also expand.

[0012]

As described in detail above, according to the present invention, it becomes possible to grow a good quality single crystal and a large diameter single crystal.

[Brief description of drawings]

FIG. 1 is a front view showing an example of the present invention.

FIG. 2 is a side view corresponding to FIG.

FIG. 3 is an enlarged view of a main part of the device according to the present invention.

[Explanation of symbols]

 1 Infrared Lamp 2 Ellipsoidal Reflector 3 Melting Part 4 Raw Material Bar 5 Seed Crystal, Growth Crystal 6 Transparent Quartz Tube 7,8 Shaft Support 9,10 Shaft Drive 11 Device Stand

Claims (6)

[Claims] 1. Radiant concentrated heating of a system in which an infrared lamp is provided at one focus of a spheroidal reflecting mirror having an inner surface as a reflective surface, and the radiation reflected from the reflective surface is concentrated and heated on the other focus. In the apparatus, an optical floating zone melting apparatus, wherein the spheroidal reflecting mirror has a spheroidal shape as its cross section and has a special shape in which the whole is ring-shaped. 2. The floating zone melting apparatus according to claim 1, wherein the spheroidal reflecting mirror has a structure capable of being divided into upper and lower parts. 3. A spheroidal reflector placed on a horizontal plane is vertically divided into three or more parts, and a mechanism for moving the second focus of the dividing line of each spheroidal reflector vertically is added. The floating zone melting apparatus of claim 1 characterized. 4. The filament shape of the halogen lamp to be used is characterized in that a filament is formed into a single wire or a spiral shape.
Floating zone melting equipment. 5. The floating zone melting apparatus according to claim 1, further comprising a mechanism for introducing cooling air into the spheroidal reflector. 6. The floating zone melting apparatus according to claim 1, further comprising a mechanism for introducing cooling air into the spheroidal reflecting mirror.